Fouling of low-pressure membranes by municipal wastewater: identification of principal foulants and underlying fouling mechanisms

Microfiltration (MF) and ultrafiltration (UF) membranes have a wide range of applications in the wastewater industry: they are used to polish wastewater treatment plant effluents or are directly integrated in the biological treatment process in the form of membrane bio-reactors (MBR). The major challenge of low-pressure membrane filtration remains the fouling of the membranes by organic matter which prevents an efficient operation by reducing the overall transmembrane flux and/or increasing the transmembrane pressure over time. This research investigates the fouling potential of municipal wastewater in low-pressure membrane filtration. Using bench-scale stirred cell experiments the principal organic foulants and the underlying fouling mechanisms are identified. Additionally, two MBR pilot plants are monitored over the course of one year in order to detect possible correlations between the feed water characteristics, operational parameters, and membrane fouling.